An anatomical view of a human stomach S and associated features is shown in FIG. 1A. The esophagus E delivers food from the mouth to the proximal portion of the stomach S. The z-line or gastro-esophageal junction Z is the irregularly-shaped border between the thin tissue of the esophagus and the thicker tissue of the stomach wall. The gastro-esophageal junction region G is the region encompassing the distal portion of the esophagus E, the z-line, and the proximal portion of the stomach S.
Stomach S includes a fundus F at its proximal end and an antrum A at its distal end. Antrum A feeds into the pylorus P which attaches to the duodenum D, the proximal region of the small intestine. Within the pylorus P is a sphincter that prevents backflow of food from the duodenum D into the stomach. The middle region of the small intestine, positioned distally of the duodenum D, is the jejunum 1.
Prosthetic devices for use in controlling obesity are shown and described in U.S. application Ser. No. 09/940,110 filed Aug. 27, 2001 and U.S. application Ser. No. 10/118,289 filed Apr. 8, 2002, and U.S. Provisional Application No. 60/379,306 filed May 10, 2002. These applications are owned by the assignee of the present application, and the disclosures of these applications are incorporated herein by reference. Certain forms of these devices involve positioning a prosthetic pouch in the proximal stomach as shown in FIG. 1B. The pouch 2 includes a proximal opening 4 and a smaller distal opening 6 and forms a small reservoir that collects masticated food from the esophagus—thereby limiting the amount of food that can be consumed at one time. As the pouch fills with food, it may distend, imparting pressure against the upper stomach and lower esophageal sphincter causing the patient to experience sensations of fullness. The pouch may additionally or alternatively act as a restrictor, limiting the amount of food intake. The pouch is fixed in place using clips, sutures, suitable adhesives or other means 8 at anchor points around the perimeter of the proximal opening 4.
The amount by which food intake should be restricted varies between patients. It may thus be desirable to increase or decrease the amount of food a patient can ingest by selecting an appropriate diameter for the pouch's distal orifice. A smaller orifice will cause food to descend from the pouch into the stomach more slowly than will a larger orifice, and will thus limit the amount of food the patient can consume at one time.
Satiation pouches may be available in multiple distal orifice sizes (and/or multiple pouch sizes) to permit the physician to select a size that is appropriate for the targeted food intake for the patient. Alternatively, satiation pouches may be configured to allow the size of the pouch's distal opening to be increased or decreased. This enables a physician implanting such a device to set the distal opening to a size appropriate for a patient. In some cases, it will also allow the physician to make adjustments to the distal opening after it has been implanted. For example, if the patient is not losing weight at a desired rate, the physician might reduce the size of the distal opening—so that food will empty more slowly from the pouch into the stomach. The physician might alternatively increase the size of the distal opening if necessary if weight loss is occurring too rapidly—or if the patient is suffering from nausea and requires that the pouch be opened to allow the patient to vomit more easily. The present application describes various satiation pouches which have adjustable distal orifice sizes and which thereby provide the physician with enhanced control over the degree of food consumed by the patient at one time.